1. Field of the Invention
The present invention relates to hydraulic couplings used in undersea drilling and production applications and seals used in those couplings. More particularly, the invention involves an undersea hydraulic coupling with three retained seals, at least one being an elastomeric seal that is restrained from radial movement into the bore of the female member by a dovetail interfit with a seal retainer, and at least one being a radial metal seal retained in the female member bore, wherein two of the seals engage different diameters on the outer circumference of the male member of the coupling.
2. Description of the Related Art
Subsea hydraulic couplings are old in the art. The couplings generally consist of a male member and a female member with soft seals positioned within the female member to seal the junction between the male and female members.
The female member is generally a cylindrical body with a relatively large diameter longitudinal bore at one end and a relatively small diameter longitudinal bore at the other. The small bore facilitates connections to hydraulic lines, while the large bore contains soft seals and receives the male portion of the coupling. The male member includes a cylindrical portion or probe at one end having a diameter approximately equal to the diameter of the large bore in the female portion of the coupling. The male member also includes a connection at its other end to facilitate connection to hydraulic lines. When the cylindrical portion of the male member is inserted into the large bore of the female member, according to the various embodiments of the device, the soft seals, or o-rings, either abut the end or face of the male member or engage the cylindrical probe wall about its outer circumference. The hydraulic fluid is then free to flow through the female and male members of the coupling, and the seals prevent that flow from escaping about the joint and the coupling.
In some instances, a check or poppet valve may be installed in the female member and also in the male member. Each valve opens when the coupling is made up and closes when the coupling is broken so as to prevent fluid from leaking out of the system of which the coupling is a part.
In U.S. Pat. No. 4,694,859 to Robert E. Smith III, assigned to National Coupling Company, Inc. of Stafford, Tex., an undersea hydraulic coupling and metal seal is disclosed. This patent provides a reusable metal seal which engages the circumference of the probe and is positioned within the female member body. The metal seal is held in place by a retainer. A clip holds the retainer within the body, preventing escape of the retainer or metal seal from the body. When the male and female portions of the coupling are parted under pressure, the retainer prevents the metal seal from blowing out through the bore of the female member.
U.S. Pat. No. 4,694,859 also discloses a soft annular seal or o-ring at the inner cylindrical surface of the retainer, which engages the probe's circumference. The soft annular seal generally is used as a secondary seal, to prevent escape of hydraulic fluid should the metal seal fail. As the probe begins to enter the retainer bore, it begins to engage a soft annular seal intermediate the retainer bore. This contact compresses the seal and creates a sliding seal between it and the probe wall. The annular seal or soft seal is of a relatively pliable material, for example, rubber or synthetic elastomer. The annular seal is generally ring-shaped and is located in a sealed groove.
U.S. Pat. No. 5,052,439 to Robert E. Smith, III, assigned to National Coupling Company, Inc. of Stafford, Tex., discloses an undersea hydraulic coupling having an elastomeric seal configured to engage the male member as it is inserted into the bore of the female member, in which the elastomeric seal is interposed between a two-piece retainer and has a dovetail interfit whereby the elastomeric seal is restrained from radial movement into the central bore and is retained in the female member upon separation of the female member and the male member. Additionally, U.S. Pat. No. 4,900,071 discloses an undersea hydraulic coupling having an elastomeric dovetail seal and an annular metal seal which also engages the outer circumference of the male member or probe wall.
In U.S. Pat. Nos. 4,832,080, 5,099,882 and 5,277,225 to Robert E. Smith, III, undersea hydraulic couplings are shown having at least two radial metal seals for sealing between the male member and the female member bore. Pressure energized seals are shown which are configured to seal radially between the male and female members, and the couplings are pressure balanced for fluid communication through mating radial passages and the annular space between the members.
Additionally, U.S. Pat. No. 5,390,702 to Robert E. Smith, III discloses an undersea hydraulic coupling having a male member with a stepped outer body that is inserted into a female member with a stepped internal bore. This step ensures that the male member is more accurately positioned and guided into the seals in the bore, ensuring greater seal reliability and longer seal life. The stepped surfaces also help prevent implosion of the seals due to sea pressure when the end of the male member comes out of the seals.
Improved sealing between the male member and female member is desirable as pressures increase at deeper ocean depths. Although the undersea hydraulic couplings of the type described above provide advantages over conventional undersea hydraulic couplings with soft seals or o-rings, it is desirable to include a third retained seal and to have seals that engage different diameters of the male member or probe.